Seventh-day Adventists are persons who neither drink nor smoke; over 40% are vegetarians. Their age distribution shows a significant proportion of older persons. In 1958, a longitudinal study of California Adventists was mounted to investigate the association of life habits with mortality and life expectancy. Results showed them to have a longer life expectancy than the general population and lower mortality rates for many chronic diseases. Since 1974, a larger group of Adventists has been studied to determine morbidity from major disease and to learn which factors in their lifestyle are associated with an extended longevity and reduced disease risk. The two separate studies have some 20,000 common enrollees but their records have not yet been linked. Objectives of the research are fourfold; 1) to ascertain the vital status of persons originally enrolled and link their records with current enrollees, thus providing a 20-year mortalitiy followup; 2) to analyze long-term results in terms of the epidemiological correlates of aging; 3) to compare mortality data of the Adventist population with a comparable population from the general public; and 4) to learn whether Adventist's extended mortality is due to selective factors or results from the unique, if somewhat variable practices of group. The methodology involves a computerized probability model to link data files of the two studies, along with trained field workers tracing church membership records. Investigation into the longevity and quality of life of the oldest members of a long-lived group seems to be appropriate at a time of steady increase in the number of elderly persons in the general population.